Conventional light transmission systems used for vehicle head lights or tail lights typically use a bulb and reflector system. In a bulb and reflector system, the filament of the bulb is placed at or near a focal point of a parabolic reflector. The light emitted by the bulb filament is collected by the reflector and reflected outward to form a light beam. A lens is used to shape the light beam into a specified pattern to satisfy vehicle lighting specifications. In a typical automotive application, a conventional bulb and reflector system collects and reflects only thirty percent of the light emitted from the bulb filament into the useful lighting area.
Bulb and reflector systems have several disadvantages, including disadvantages related to aerodynamics and aesthetic styling. For example, the depth of the reflector along its focal axis and the height of the reflector in directions perpendicular to the focal axis greatly limit attempts at streamlining vehicle contours. Additionally, thermal energy given off by the bulb during operation must be considered. The size of the reflector as well as the material used in its construction vary depending upon the amount of thermal energy generated by the bulb filament. Decreasing the size of the reflector requires use of materials with high thermal resistivity for the reflector.
One approach to develop an automotive lighting system for use with newer streamlined body designs is proposed in U.S. Pat. No. 5,434,754, assigned to the assignee of the present invention, which discloses the combination of a fiber optic light guide which transmits light from a remote light source, to an optical element having a parabolic reflector, a light manifold, and a kicker. A manifold is necessary to expand the incoming light for distribution across the kicker. One problem with such an arrangement is that the manifold takes up approximately one third of the overall foot print of the optical element. The unlit area required for the manifold is a liability when considering packaging and space limitations associated with vehicle design.
Therefore, it would be desirable to provide a laser illuminated, uniform thickness, thin sheet optic lighting system for a vehicle which accommodates manufacturing and thermal considerations as well as the limitations dictated by vehicular aerodynamic and styling requirements.